Initial phase control of an oscillator

Abstract

An initial phase control for an oscillator such as a differential ring voltage-controlled oscillator is disclosed. The initial phase control generally comprises a current source circuit coupled to a first node of the delay cell and a current provider. The current source circuit and current provider are preferably selectively and synchronously in an on or off state such that when the current source circuit and current provider are in an on state, the current source circuit draws a current through the first node of the delay cell and the current provider provides current through a second node of the delay cell. A method for controlling a delay cell and an initial phase control for a differential ring oscillator having a plurality of delay cells in a ring configuration are also disclosed.

What is claimed is:  
     
       1. An initial phase control for a delay cell, comprising: 
       a current source circuit coupled to a first node of the delay cell;  
       a current provider; and  
       an initial phase controller including at least one switch coupled to said current source circuit and to said current provider to set an initial phase of the delay cell output such that the current source circuit and current provider are selectively and synchronously in an on or off state such that when the current source circuit and current provider are in an on state, the current source circuit draws a current through the first node of the delay cell and the current provider provides current through a second node of the delay cell and such that the phase of the delay cell output of the is started in a predetermined initial phase,  
       wherein the initial phase controller includes a reset switch and a transistor, the reset switch is coupled between a power supply and the transistor, the transistor having collector, base, and emitter nodes coupled to said power supply, the reset switch, and the second node of the delay cell, respectively.  
     
     
       2. The initial phase of claim  1 , wherein the transistors is a bipolar junction transistor. 
     
     
       3. An initial phase control for a delay cell, comprising: 
       a current source circuit coupled to a first node of the delay cell;  
       a current provider; and  
       an initial phase controller including at least one switch coupled to said current source circuit and to said current provider to set an initial phase of the delay cell output such that the current source circuit and current provider are selectively and synchronously in an on or off state such that when the current source circuit and current provider are in an on state, the current source circuit draws a current through the first node of the delay cell and the current provider provides current through a second node of the delay cell and such that the phase of the delay cell output is started in a predetermined initial phase,  
       wherein the initial phase controller includes a set switch, a first reset switch, and a current source coupled to ground, wherein the set switch is coupled between a power supply and the current source and the first reset switch is coupled between the first node and the current source.  
     
     
       4. The initial phase control of claim  3 , wherein the initial phase controller includes a second reset switch and a transistor, the second reset switch is coupled between said power supply and the transistor, the transistor having collector, base, and emitter nodes coupled to said power supply, the second reset switch, and the second node of the delay cell, respectively. 
     
     
       5. The initial phase control of claim  3 , wherein the set and reset inputs are of same amplitude and opposite in phase. 
     
     
       6. A method for controlling a delay cell, comprising: 
       inputting a set input to a current source circuit;  
       inputting a reset input to the current source circuit and a current provider, the set and reset input selectively and synchronously transition the current source circuit and the current provider between an on and off state such that when the current source circuit and current provider are in an on state, the current source circuit draws a current through a first node of the delay cell and the current provider provides current through a second node to the delay cell such that the phase of an output of the delay cell is started in a predetermined initial phase,  
       wherein inputting the set input to the current source circuit includes inputting the set input to a set switch of the current source circuit, the set switch is coupled between a power supply and a current supply of the current source circuit.  
     
     
       7. A method for controlling a delay cell, comprising: 
       inputting a set input to a current source circuit;  
       inputting a reset input to the current source circuit and a current provider, the set and reset input selectively and synchronously transition the current source circuit and the current provider between an on and off state such that when the current source circuit and current provider are in an on state, the current source circuit draws a current through a first node of the delay cell and the current provider provides current through a second node to the delay cell such that the phase of an output of the delay cell is started in a predetermined initial phase,  
       wherein inputting a reset input to the current source circuit includes inputting the reset input to a reset switch of the current source circuit, the reset switch is coupled between the current supply of the current source circuit and the first node of the delay cell.  
     
     
       8. A method for controlling a delay cell, comprising: 
       inputting a set input to a current source circuit;  
       inputting a reset input to the current source circuit and a current provider, the set and reset input selectively and synchronously transition the current source circuit and the current provider between an on and off state such that when the current source circuit and current provider are in an on state, the current source circuit draws a current through a first node of the delay cell and the current provider provides current through a second node to the delay cell such that the phase of an output of the delay cell is started in a predetermined initial phase,  
       wherein inputting a reset input to the current provider includes inputting the reset input to a reset switch of the current provider, the reset switch is coupled between a power supply and a base node of a transistor of the current provider, a collector and emitter node of the transistor are coupled to the power supply and the second node of the delay cell, respectively.  
     
     
       9. A differential ring oscillator with initial phase control and having a plurality of delay cells in a ring configuration, comprising: 
       a first delay cell, one or more intermediate delay cells, and a last delay cell, wherein each delay cell is adapted to receive a first input and a second input and wherein each delay cell has a first output node and a second output node, wherein the delay cells are configured in a sequential ring configuration such that the first and second output nodes of the last delay cell are coupled to the second and first inputs of the first delay cell, respectively, and the first and second output nodes of each of the first and intermediate delay cells are coupled to the first and second inputs of a subsequent delay cell comprising the intermediate and the last delay cells, respectively; and  
       at least one initial phase control circuit, each initial phase control circuit coupled to one of the delay cells, each initial phase control circuit comprising:  
       a current source circuit coupled to a first node of the delay cell to which the control circuit is coupled;  
       a current provider; and  
       an initial phase controller including at least one switch coupled to said current source circuit and to said current provider to set an initial phase of said delay cell to which the control circuit is coupled such that the current source circuit and current provider are selectively and synchronously in an on or off state such that when the current source circuit and current provider are in an on state, the current source circuit draws a current through the first node of the delay cell to which the control circuit is coupled and the current provider provides current through a second node of the delay cell to which the control circuit is coupled,  
       wherein the initial phase controller includes a reset switch and a transistor, the reset switch is coupled between a power supply and the transistor, the transistor having collector, base, and emitter nodes coupled to said power supply, the reset switch, and the second node of the delay cell to which the control circuit is coupled, respectively.  
     
     
       10. A differential ring oscillator with initial phase control and having a plurality of delay cells in a ring configuration, comprising: 
       a first delay cell, one or more intermediate delay cells, and a last delay cell, wherein each delay cell is adapted to receive a first input and a second input and wherein each delay cell has a first output node and a second output node, wherein the delay cells are configured in a sequential ring configuration such that the first and second output nodes of the last delay cell are coupled to the second and first inputs of the first delay cell, respectively, and the first and second output nodes of each of the first and intermediate delay cells are coupled to the first and second inputs of a subsequent delay cell comprising the intermediate and the last delay cells, respectively; and  
       at least one initial phase control circuit, each initial phase control circuit coupled to one of the delay cells, each initial phase control circuit comprising:  
       a current source circuit coupled to a first node of the delay cell to which the control circuit is coupled;  
       a current provider; and  
       an initial phase controller including at least one switch coupled to said current source circuit and to said current provider to set an initial phase of said delay cell to which the control circuit is coupled such that the current source circuit and current provider are selectively and synchronously in an on or off state such that when the current source circuit and current provider are in an on state, the current source circuit draws a current through the first node of the delay cell to which the control circuit is coupled and the current provider provides current through a second node of the delay cell to which the control circuit is coupled,  
       wherein the initial phase controller includes a set switch, a first reset switch, and a current source coupled to ground, wherein the set switch is coupled between a power supply and the current source and the first reset switch is coupled between the first node of the delay cell to which the control circuit is coupled and the current source.  
     
     
       11. The differential ring oscillator of claim  10 , wherein the initial phase controller includes a second reset switch and a transistor, the second reset switch is coupled between said power supply and the transistor, the transistor having collector, base, and emitter nodes coupled to said power supply, the second reset switch, and the second node of the delay cell to which the control circuit is coupled, respectively. 
     
     
       12. The differential ring oscillator of claim  10 , wherein the set and reset inputs are of same amplitude and opposite in phase.